diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 637052b230421183e46981af975a4b5fbd31de43..18247a7bf33563df194edc3875cb8805b837b6b0 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -50,8 +50,8 @@ static struct bcache_ops no_sc_ops = {
 
 struct bcache_ops *bcops = &no_sc_ops;
 
-#define cpu_is_r4600_v1_x()	((read_c0_prid() & 0xfffffff0) == 0x2010)
-#define cpu_is_r4600_v2_x()	((read_c0_prid() & 0xfffffff0) == 0x2020)
+#define cpu_is_r4600_v1_x()	((read_c0_prid() & 0xfffffff0) == 0x00002010)
+#define cpu_is_r4600_v2_x()	((read_c0_prid() & 0xfffffff0) == 0x00002020)
 
 #define R4600_HIT_CACHEOP_WAR_IMPL					\
 do {									\
diff --git a/arch/mips/mm/pg-r4k.c b/arch/mips/mm/pg-r4k.c
index 75d9ebfc54316ff59a8a995594f515a7d89abe83..c9e6ee2a8a2391ee25e7046427593e3025eb5aee 100644
--- a/arch/mips/mm/pg-r4k.c
+++ b/arch/mips/mm/pg-r4k.c
@@ -25,7 +25,10 @@
 #include <asm/cpu.h>
 #include <asm/war.h>
 
-#define half_scache_line_size()		(cpu_scache_line_size() >> 1)
+#define half_scache_line_size()	(cpu_scache_line_size() >> 1)
+#define cpu_is_r4600_v1_x()	((read_c0_prid() & 0xfffffff0) == 0x00002010)
+#define cpu_is_r4600_v2_x()	((read_c0_prid() & 0xfffffff0) == 0x00002020)
+
 
 /*
  * Maximum sizes:
@@ -198,14 +201,14 @@ static inline void build_cdex_p(void)
 	if (store_offset & (cpu_dcache_line_size() - 1))
 		return;
 
-	if (R4600_V1_HIT_CACHEOP_WAR && ((read_c0_prid() & 0xfff0) == 0x2010)) {
+	if (R4600_V1_HIT_CACHEOP_WAR && cpu_is_r4600_v1_x()) {
 		build_nop();
 		build_nop();
 		build_nop();
 		build_nop();
 	}
 
-	if (R4600_V2_HIT_CACHEOP_WAR && ((read_c0_prid() & 0xfff0) == 0x2020))
+	if (R4600_V2_HIT_CACHEOP_WAR && cpu_is_r4600_v2_x())
 		build_insn_word(0x8c200000);	/* lw      $zero, ($at) */
 
 	mi.c_format.opcode     = cache_op;
@@ -361,7 +364,7 @@ void __init build_clear_page(void)
 
 	build_addiu_a2_a0(PAGE_SIZE - (cpu_has_prefetch ? pref_offset_clear : 0));
 
-	if (R4600_V2_HIT_CACHEOP_WAR && ((read_c0_prid() & 0xfff0) == 0x2020))
+	if (R4600_V2_HIT_CACHEOP_WAR && cpu_is_r4600_v2_x())
 		build_insn_word(0x3c01a000);	/* lui     $at, 0xa000  */
 
 dest = label();
@@ -417,7 +420,7 @@ void __init build_copy_page(void)
 
 	build_addiu_a2_a0(PAGE_SIZE - (cpu_has_prefetch ? pref_offset_copy : 0));
 
-	if (R4600_V2_HIT_CACHEOP_WAR && ((read_c0_prid() & 0xfff0) == 0x2020))
+	if (R4600_V2_HIT_CACHEOP_WAR && cpu_is_r4600_v2_x())
 		build_insn_word(0x3c01a000);	/* lui     $at, 0xa000  */
 
 dest = label();